Funny...
My First: G&P WOC13 GBBR -Broke, so I tried to sell as I was building my 2nd GBBR, but fix it before it sold. (Front Upper Receiver tab broke. Replaced it instead)
Second: Prime DIY GBBR -Got sick of cool down effect and fixing it
Third: Systema PTW -God I hate aegs, the motors...ugh
Fourth: Daytonagun AKS74U, aside from the problem encounter in the beginning, love it (still looking for a brand of mag that feeds 100%)